THE METAMORPHOSIS OF A CRAB. 217 



1. The carapace (Fig. 110, c) has no lateral spines, and 

 either no dorsal spine or a very small one. 



2. The eyes (Fig. 110, E) are at the ends of very 

 movable stalks. 



3. The five pairs of pereiopods are fully developed, and 

 are very similar to those of the adult. 



4. The gills have made their appearance, above the 

 bases of the pereiopods, under the lateral margin of the 

 carapace, but these margins are still free, as they are in 

 the zoea. 



5. The maxillipeds are no longer organs of locomotion, 

 and there are three pairs. 



6. While the larva is still able to swim, it also moves 

 over the bottom by walking upon the tip of the pereiopods, 

 with a crab-like gait, very similar to that of the adult. 



b. It differs from the adult in the following conspicuous 

 features : 



1. There is a long, pointed rostrum (Fig. 110, r) at 

 the anterior end of the carapace. 



2. The eyes (E} are not covered by the carapace, and 

 they are not upon the anterior edge, but upon the sides of 

 a median frontal region. 



3. Both antennules and antennae project from beneath 

 the edge of the carapace, and the flagella of the an- 

 tenna (-4) are very long. 



4. In Callinectes, and in many other species, the fifth 

 pair of pereiopods (pr. 5) are bent upwards and backwards 

 above the dorsal surface of the carapace. 



5. The segment (7) which carries them is movable. 



6. There is a long, movable, six-jointed abdomen (a&), 

 which carries five or six pairs of biramous swimming-feet, 

 and ends in a small, rounded telson. While the animal is 

 swimming the telson is stretched out behind the carapace, 



